Unique clocks are a mainstay around here, and while plenty are “human readable” without any instruction, there are a few that take a bit of practice before someone can glean the current time from them. Word clocks are perhaps on the easier side of non-traditional displays but at the other end are binary clocks or even things like QR code clocks. To get the best of both worlds, though, multiple clock faces can be combined into one large display like this clock build from [imitche3].

The clock is actually three clocks in one. The first was inspired by a binary clock originally found in a kit, which has separate binary “digits” for hour, minute, and second and retains the MAX 7219 LED controller driving the display. A standard analog clock rests at the top, and a third clock called a retrograde clock sits at the bottom with three voltmeters that read out the time in steps. Everything is controlled by an Arduino Nano with the reliable DS3231 keeping track of time. The case can be laser-cut or 3D printed and [imitche3] has provided schematics for both options.

As far as clocks builds go, we always appreciate something which can be used to tell the time without needing any legends, codes, or specialized knowledge. Of course, if you want to take a more complex or difficult clock face some of the ones we’re partial to are this QR code clock which needs a piece of hardware to tell the time that probably already has its own clock on it.

[Thomas] found an interesting probable millivoltmeter with some Beckman displays. Like many instruments from that time period, this one had a lot of tobacco smoke residue inside. The display unit inside had a sticker that not only showed the company that made it, but also had their Telex number on it, another sign of the times. You can see the device in the video below.

The unit looked like a one-off made by a hobbyist or a technician but the case looked suspiciously like old Bang and Olfusen equipment. Someone in the video comments mentions it was built for the service department.

Some of the wiring had not survived well and there was a broken display digit. What’s more, is the millivolt marking applied to the display. The actual instrument has dividers that provide readings in volts, not millivolts.

That Beckman display is very retro and [Thomas] breaks into that subassembly if you fancy a peek inside. Beckman made some interesting displays. Voltmeters sure have changed over the years.

The instrument which probably the greatest number of Hackaday readers own is likely to be the humble digital multimeter. They’re cheap and useful, but they’re single-channel, and difficult to incorporate into a breadboard project. If you’ve ever been vexed by these limitations then [Alun Morris] has just the project for you, in the world’s smallest auto-ranging multichannel voltmeter. It’s a meter on a tiny PCB with a little OLED display, and as its name suggests, it can keep an eye on several voltages for you.

At its heart is an ATtiny1614 microcontroller on a custom PCB, but for us the part we most like lies not in that but in the prototype version made on a piece of protoboard. There’s considerable soldering skill in bending surface mount components to your will on this material, and though these aren’t quite the smallest parts it’s still something that must have required some work under the magnifier.

All of the code and hardware details can be found in the GitHub repository, and for your viewing pleasure there’s a video showing it in action which we’ve placed below.

With the demands of modern computing, from video editing, streaming, and gaming, many of us will turn to a monitoring system of some point to keep tabs on CPU usage, temperatures, memory, and other physical states of our machines. Most are going to simply display on the screen but this data can be sent to external CPU monitors as well. This retro-styled monitor built on analog voltmeters does a great job of this and adds some flair to a modern workstation as well.

The build, known as bbMonitor, is based on the ESP32 platform which controls an array of voltmeters via PWM. The voltmeters have been modified with a percentage display to show things like CPU use percentage. Software running on the computers sends this data in real time to the ESP32 so the computer’s behavior can be viewed at a glance. Each voltmeter is also augmented with RGB LEDs that change color from green to red as use increases as well. The project’s creator, [Corebb], also notes that the gauges will bounce around if the computer is under heavy load but act more linearly when under constant load, also helping to keep an eye on computer status.

While the build does seem to rely on a Windows machine to run the software for export to the monitor, all of the code is open-sourced and available on the project’s GitHub page and could potentially be adapted for other operating systems. And, as far as the voltmeters themselves go, there have been similar projects in the past that use stepper motors as a CPU usage monitor instead.